It has been proposed to examine the specific surface distribution of pulp using various techniques. For example, Canadian Pat. No. 1,045,866 issued Jan. 7, 1979 to Karnis and Wood described a technique utilizing a plurality of hydrocyclones arranged in series and measuring the various property of the accepts and rejects for these hydrocyclones. In this arrangement the accepts and/or rejects were individually collected and measured, the feed consistency adjusted and then pumped to the next hydrocyclones in the sequence to result in relative lengthy operation.
The fractionator described in the said Canadian patent was then superceded by a fractionator described in U.S. Pat. No. 4,135,389 issued Jan. 23, 1979 again to Karnis and Wood. This latter device is composed of a plurality of chambers with a hydrocyclone moveably mounted and connected to the various chambers so that the accepts or rejects as desired may be recycled through the hydrocyclone and various samples so produced analysed for specific surface. The procedure required to operate this device is time consuming in that it requires collecting a fraction, diluting the fraction to proper consistency and measuring the relevant properties and then feeding the diluted sample at the proper consistency through the hydrocyclone to provide another fraction and repeating the procedure.